1. Field of the Invention
The present invention relates to a keyboard in which keytops are attached to the opening portion formed in a frame of an electronic apparatus.
2. Description of the Prior Art
Keyboards for use in input apparatuses of electronic apparatuses are generally constituted such that keytops extend through a plurality of key holes formed in the frame.
Recently, in such electronic apparatus, there is a tendency to add various functions, such as time clock, alarm, etc., and simultaneously realization of a miniaturized and thin apparatus is intended for the purposes of energy saving and ease in handling, etc. Therefore, there is also a tendency such that the number of keytops in the keyboard of such a kind of electronic apparatus increases and its shape is also miniaturized and thinned, so that various problems are caused in assembling processes and efficiency in maintenance and inspection. The conventional structure consequently has a problem such that it takes considerable time and labor for assembling the keyboard.
Practically speaking, a conventional keyboard generally has a structure in which a keytop with a flange is brought into engagement with a key hole from the back surface (lower surface) of a frame (upper casing) and a spring built in the space between the frame and a lower casing (lower frame) contacts the back surface of the keytop, and thereby applying an upward recovery force to the keytop.
Therefore, if the upper and lower casings are separated for adjustment, inspection or the like of electronic parts, each keytop is removed and dispersed from the frame, so that this causes a problem such that not only is a large amount of labor required for reassembly but also the keytops can be easily erroneously inserted. In this case, each keytop has to be inserted from the back side of the frame and it is difficult to check the character or symbol printed on the upper surface of the keytop upon insertion; therefore, a serious problem is caused in case of a keyboard having a number of keytops and a countermeasure for such a problem is in strong demand.
On the other hand, there has been adopted a method whereby a monolithic thin leaf spring is used as a keytop return spring thereby to reduce the number of parts. However, a flat and thin leaf spring cannot be used in the foregoing conventional structure and the bending or reducing process is needed upon manufacturing. Consequently, there are problems such that handling is inconvenient and the number of assembly operations is large.